Fixed flake8 errors in four more files

Vacations/convert.py

-from icalendar import Calendar, Event, Timezone
-import pytz
+from icalendar import Calendar, Event
 from datetime import datetime
 import os
 

ess/SP_Relativity.py

@@ -62,7 +62,7 @@ def beta_from_gamma(gamma):
 
     raises
     ------
-    if given gamma is smaller than one raises a warning 
+    if given gamma is smaller than one raises a warning
     """
     if gamma < 1:
         print("gamma cannot be less than one")
@@ -124,9 +124,9 @@ def energy(gamma_beta, mass=proton_mass_in_MeV):
     -------
     returns kinetic energy of the particle in MeV.
 
-    
-    example: 
-    sprel.energy(2.55, 938) 
+
+    example:
+    sprel.energy(2.55, 938)
     > 1453.8999999999999
     if gamma_beta < 1 the value is beta
     example:
@@ -146,24 +146,24 @@ def emit_geo(u_up_array):
     ----------
     u_up_array: array like
         a 2D array containing that has u_up_array[:,:2] as coordinates in u and u'
-        
+
     returns
     -------
     geometrical emittance of the distribution/array in units of pi.mm.mrad
     """
     import numpy as np
 
-    u_shift = u_up_array[:, 0]  #  x
-    up_shift = u_up_array[:, 1]  #  x'
+    u_shift = u_up_array[:, 0]  # x
+    up_shift = u_up_array[:, 1]  # x'
     u = u_shift - np.average(u_shift)
     up = up_shift - np.average(up_shift)
-    u2 = np.square(u)  #  x2
+    u2 = np.square(u)  # x2
     u2ave = np.average(u2)  # <x2>
     # print(u2ave)
-    up2 = np.square(up)  #  x'2
+    up2 = np.square(up)  # x'2
     up2ave = np.average(up2)  # <x'2>
     # print(up2ave)
-    uup = np.multiply(u, up)  #  x.x'
+    uup = np.multiply(u, up)  # x.x'
     uupave = np.average(uup)  # <x.x'>
     uupave2 = uupave ** 2  # <x.x'>2
     # print(uupave2)

ess/installed.py

@@ -10,9 +10,6 @@ def get_installed_packages():
     import pip
 
     installed_packages = pip.get_installed_distributions()
-    installed_packages_list = sorted(
-        ["%s==%s" % (i.key, i.version) for i in installed_packages]
-    )
     return installed_packages
 
 

examples/fieldmap/example.py

@@ -4,7 +4,7 @@ import os
 """
 Example
 
-The parameters in the following six rows define the path to your fieldmap, no name is needed, this script 
+The parameters in the following six rows define the path to your fieldmap, no name is needed, this script
 scans the folder and converts all files, assumes all are binary fieldmaps, to ASCII fieldmaps.
 The dimension of the field is also needed.
 If you need to cut the field, the n_enter and n_exit should be adjusted.